A terahertz (THz) spatial light modulator implemented with metamaterial absorbers (MMAs) functionalized with isothiocyanate‐based liquid crystals (LCs) is experimentally demonstrated. The device is designed to work in reflection mode and is arranged in a 6 × 6 pixel matrix where the response of each pixel is modulated by electronically controlling the orientation of liquid crystal dimers covering the entire metamaterial absorber landscape. Experiments show that each pixel can be controlled independently and that pixelated absorption patterns can be created at will. The SLM shows an overall modulation depth of 75%. Furthermore, computational results show that losses arising from LCs impose a severe limitation on the overall performance and that consequently the modulation depth of each pixel could be improved with liquid crystal mixtures designed primarily for THz frequencies. This work demonstrates the viability of liquid crystal‐based reconfigurable metamaterials and highlights their great potential use for future state‐of‐the‐art THz devices.
We have developed a heat shield based on a metamaterial engineering approach
to shield a region from transient diffusive heat flow. The shield is designed
with a multilayered structure to prescribe the appropriate spatial profile for
heat capacity, density, and thermal conductivity of the effective medium. The
heat shield was experimentally compared to other isotropic materials.Comment: 8 pages, 5 figures, 1 table, accepted on Applied Physics Lette
Spatial tailoring of the material constitutive properties is a well-known strategy to mold the local flow of given observables in different physical domains. Coordinate-transformation-based methods (e.g., transformation optics) offer a powerful and systematic approach to design anisotropic, spatially-inhomogeneous artificial materials ("metamaterials") capable of precisely manipulating wave-based (electromagnetic, acoustic, elastic) as well as diffusion-based (heat) phenomena in a desired fashion. However versatile these approaches have been, most designs have so far been limited to serving single-target functionalities in a given physical domain. Here we present a step towards a "transformation multiphysics" framework that allows independent and simultaneous manipulation of multiple physical phenomena. As a proof of principle of this new scheme, we design and synthesize (in terms of realistic material constituents) a metamaterial shell that simultaneously behaves as a thermal concentrator and an electrical "invisibility cloak".Our numerical results open up intriguing possibilities in the largely unexplored phase space of multi-functional metadevices, with a wide variety of potential applications to electrical, magnetic, acoustic, and thermal scenarios.
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ABSTRACTWe demonstrate an innovative multifunctional artificial material that combines exotic metamaterial properties and the environmentally responsive nature of phase change media. The tunable metamaterial is designed with the aid of two interwoven coordinatetransformation equations and implemented with a network of thin film resistors and vanadium dioxide (V O 2 ). The strong temperature dependence of V O 2 electrical conductivity results in a relevant modification of the resistor network behavior, and we provide experimental evidence for a reconfigurable metamaterial electric circuit (MMEC) that not only mimics a continuous medium but is also capable of responding to thermal stimulation through dynamic variation of its spatial anisotropy. Upon external temperature change the overall effective functionality of the material switches between a "truncated-cloak" and "concentrator" for electric currents. Possible applications may include adaptive matching resistor networks, multifunctional electronic devices, and equivalent artificial materials in the magnetic domain. Additionally, the proposed technology could also be relevant for thermal management of integrated circuits.
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